Nanotubos de nitreto de gálio e nitreto de alumínio

Abstract

We performed a study of the electronic structure of gallium nitride (GaN) and aluminium nitride (AlN) nanotubes, Al x Ga 1-x N nanotube alloys, as well as heterojunctions between GaN/AlN and Al x Ga 1-x N/AlN nanotubes. Our calculations were done using the density functional theory (DFT) within the local density approximation for the exchange and correlation term. We studied (10,0) GaN, AlN nanotubes and their alloys using unit cells contained 120 atoms, which corresponds to three primitive unit cells along the axis. The properties of the alloy nanotubes Al x Ga 1-x N where determined through an average over five different independent random configuration for each composition. We determined the band gaps for the pure nanotubes and their alloys. A quadratic fit of the band gap values as a function of the Al concentration shows a bowing coefficient of -0,1442 eV. We also determined the average electrostatic potential for the nanotubes and alloys, and performed a quadratic fit of these values obtaining a bowing coefficient of -0,2799 eV. We calculated the valence band offset of the GaN/AlN heterojunction and estimated the band offset for the Al x Ga 1-x N/GaN heterojunctions. All studied heterojunctions present type II band offset.